The different crystallographic structures of manganese dioxide (alpha-MnO2, (beta-MnO2, gamma-MnO2 and delta-MnO2) were prepared via simple and feasible methods. Among four crystallographic structures, gamma-MnO2 exhibited the best electrochemical property and was chosen to compound gamma-MnO2/polyaniline (PANI) composite electrode through in situ synthesis techniques. The as-prepared samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). The electrochemical properties of as-prepared samples influenced by the different mass ratios, scan rates, and current dehsities were mainly investigated by cyclic voltammetry (CV), galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS), and cycle life, respectively. The results showed that the specific capacitance can be up to 493 F g(-1) as mass ratio of gamma-MnO2/PANI was 1:5 at current density of 0.5 A g(-1), suggesting the gamma-MnO2/PANI (1:5) composite as an electrode material for super capacitors has great development prospects. (C) 2017 Elsevier B.V. All rights reserved.